Harnessing a Quantum Design Approach for Making Low-Loss Superlenses

Nano Letters, Article ASAP (2016)

Recently, so-called “superlenses”, made from metamaterials that are structured on a length scale much less than an optical wavelength, have shown impressive diffraction-beating image resolution, but they use materials with negative dielectric responses, and they absorb much of the light in a way that seriously degrades both the resolution and brightness of the image. Here we demonstrate an alternative “quantum metamaterials” (QM) approach that uses materials structured at the nanoscale, i.e., comparable to an electron wavelength. This allows us to use quantum mechanical design principles to generate structures with a highly elliptical isofrequency dispersion characteristic that circumvents this loss problem. The physics of the loss improvement is analyzed analytically and the QM superlens subdiffraction imaging is modeled numerically, with a finite-element method. Finally, we demonstrate a working QM superlens device, utilizing intersubband transitions between the confined electron states in a III–V semiconductor multiquantum-well. It images down to a resolution of better than ∼λ/10 and has loss figures improved by roughly a decade over previous “classical” designs. This QM approach is an alternative paradigm for designing radiation-manipulating devices and offers the prospect of practical super-resolving devices at new wavelengths and geometries.